US10475366B2 - Display device and method for driving display device - Google Patents

Display device and method for driving display device Download PDF

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US10475366B2
US10475366B2 US15/839,146 US201715839146A US10475366B2 US 10475366 B2 US10475366 B2 US 10475366B2 US 201715839146 A US201715839146 A US 201715839146A US 10475366 B2 US10475366 B2 US 10475366B2
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luminance
areas
segment
subsegment
area
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US20180166002A1 (en
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Kazuhiko Sako
Tsutomu Harada
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Japan Display Inc
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Japan Display Inc
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2003—Display of colours
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2074—Display of intermediate tones using sub-pixels
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/3413—Details of control of colour illumination sources
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/342—Control of illumination source using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
    • G09G3/3426—Control of illumination source using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines the different display panel areas being distributed in two dimensions, e.g. matrix
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3607—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0243—Details of the generation of driving signals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0264—Details of driving circuits
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals

Definitions

  • the present invention relates to a display device and a method for driving the display device.
  • Display devices employing local dimming technology include multi-display devices that control an area illuminated by a backlight in a manner dividing the area into a plurality of segment areas (for example, Japanese Patent Application Laid-open Publication No. 2013-246426).
  • the light quantity is sometimes supplemented by additional light sources located in the periphery of a light source corresponding to the part.
  • a routine to assign light quantities to the light sources supplementing the light quantity from the periphery is fixed, and has no relation with the luminance distribution of the part that requires the large light quantity in the display area. As a result, only a particular light source is lit up to supplement the light quantity from the periphery, which may cause a load on the particular light source.
  • unevenness of the light quantity represented by the luminance distribution of the part that requires the large light quantity sometimes disagrees with the locations of the light sources that supplement the light quantity of the part from the periphery.
  • the display output image is updated such that the part requiring the large light quantity shifts away from the positions corresponding to the light sources that supplement the light quantity of the part with light from the periphery, a light source different from the light source having supplemented the light quantity from the periphery is suddenly lit up. Consequently, the sudden change in the luminance distribution sometimes causes deterioration in display quality.
  • a display device includes: an image display panel having a display area in which display is controlled based on an image signal; a light source device configured to illuminate the image display panel with a plurality of light sources; and a controller configured to control a lighting amount of each of the light sources based on the image signal.
  • the display area includes a plurality of segment areas each illuminated by one or more of the light sources. Each of the segment areas includes a plurality of subsegment areas that are obtained by further dividing the segment area.
  • the controller is configured to: calculate luminance required for each of the subsegment areas, based on the image signal for each of the subsegment areas; temporarily set luminance values of the respective segment areas for determining the lighting amounts of the light sources based on maximum luminance among the required luminance values of the respective subsegment areas included in each of the segment areas; and reset, based on at least the maximum luminance among the required luminance values of the respective subsegment areas included in each of the segment areas, the luminance value of at least the segment area adjacent to the corresponding subsegment area having the required luminance of the maximum luminance.
  • FIG. 1 is a block diagram illustrating an exemplary configuration of a display device according to a first embodiment of the present invention
  • FIG. 2 is a diagram illustrating a pixel array of an image display panel according to the first embodiment
  • FIG. 3 is a schematic diagram illustrating a configuration example of a light source device
  • FIG. 4 is a diagram illustrating an exemplary relation between luminance of each of a plurality of light sources arranged along a row direction and a luminance distribution of the entire light source row;
  • FIG. 5 is a graph schematically illustrating a flow of determination processing of lighting amounts of the light sources based on the luminance distribution of the light source device;
  • FIG. 6 is a graph schematically illustrating the flow of the determination processing of the lighting amounts of the light sources based on the luminance distribution of the light source device;
  • FIG. 7 is a graph schematically illustrating the flow of the determination processing of the lighting amounts of the light sources based on the luminance distribution of the light source device;
  • FIG. 8 is a graph schematically illustrating the flow of the determination processing of the lighting amounts of the light sources based on the luminance distribution of the light source device;
  • FIG. 9 is a graph schematically illustrating the flow of the determination processing of the lighting amounts of the light sources based on the luminance distribution of the light source device;
  • FIG. 10 is a diagram schematically explaining a method for selecting light sources to be changed in lighting amount
  • FIG. 11 is a graph illustrating an example of resetting of a temporary setting
  • FIG. 12 is a functional block diagram illustrating a functional configuration example of a signal processor
  • FIG. 13 is a subblock diagram of a lighting amount calculator
  • FIG. 14 is a schematic diagram illustrating an example of luminance required for a plurality of segment areas
  • FIG. 15 is a schematic diagram illustrating an example of luminance required for a plurality of subsegment areas
  • FIG. 16 is a schematic diagram illustrating a calculation example of required luminance of other segment areas based on the luminance required for the respective subsegment areas included in one segment area;
  • FIG. 17 is a schematic diagram illustrating an example of the luminance of the segment areas after being reset
  • FIG. 18 is a diagram illustrating an example of a correspondence relation between a segment area where luminance is insufficient, a subsegment area exhibiting the maximum luminance in the segment area, and segment areas corresponding to positions of light sources to be subjected to adjacent light source lighting amount correction for increasing the lighting amounts in order to supplement the insufficient luminance, and an execution order of the light source lighting amount correction;
  • FIG. 19 is a schematic diagram illustrating an example of the luminance of the segment areas after being subjected to the adjacent light source lighting amount correction
  • FIG. 20 is a conceptual diagram of an extended HSV color space reproducible by the display device of the embodiment.
  • FIG. 21 is an exemplary flowchart of processing to obtain a light source drive signal
  • FIG. 22 is an exemplary flowchart of calculation processing of the light source lighting amount correction illustrated in FIG. 21 ;
  • FIG. 23 is a block diagram illustrating an exemplary configuration of a display device according to a second embodiment of the present invention.
  • FIG. 24 is a diagram illustrating another example of the correspondence relation between the segment area where the luminance is insufficient, the subsegment area exhibiting the maximum luminance in the segment area, and the segment areas corresponding to the positions of the light sources to be subjected to the adjacent light source lighting amount correction for increasing the lighting amounts in order to supplement the insufficient luminance, and the execution order of the light source lighting amount correction;
  • FIG. 25 is a schematic diagram illustrating a setting example of the segment areas and the subsegment areas of the image display panel according to a first modification
  • FIG. 26 is a diagram illustrating an arrangement example of light sources of a light source device according to the first modification
  • FIG. 27 is a schematic diagram illustrating a setting example of the segment areas and the subsegment areas of the image display panel according to a second modification
  • FIG. 28 is a diagram illustrating an arrangement example of light sources of a light source device according to the second modification
  • FIG. 29 is a schematic diagram illustrating a setting example of the segment areas and the subsegment areas of the image display panel according to a third modification
  • FIG. 30 is a schematic diagram illustrating a setting example of the segment areas and the subsegment areas of the image display panel according to a fourth modification
  • FIG. 31 is a diagram illustrating a configuration example of a light source device according to a fifth modification.
  • FIG. 32 is a schematic diagram illustrating a setting example of the segment areas and the subsegment areas of the image display panel according to the fifth modification.
  • the element when an element is described as being “on” another element, the element can be directly on the other element, or there can be one or more elements between the element and the other element.
  • FIG. 1 is a block diagram illustrating an exemplary configuration of a display device according to a first embodiment of the present invention.
  • FIG. 2 is a diagram illustrating a pixel array of an image display panel according to the first embodiment.
  • a display device 10 includes a signal processor 20 , an image display panel (display unit) 30 , an image display panel driver 40 , a light source device 50 , and a light source device driver 60 .
  • the signal processor 20 receives an unprocessed signal BD serving as an input signal of an original image and control data OD from a control device 11 , and outputs a processed signal AD and a light source drive signal BL to control operations of the display device 10 .
  • the image display panel (display unit) 30 has a display area in which display is controlled on the basis of the processed signal AD serving as an image signal, and displays an image in the display area.
  • the image display panel driver 40 controls driving of the image display panel 30 .
  • the light source device 50 serves as a backlight that illuminates the image display panel 30 from the back side thereof.
  • the light source device driver 60 controls drive of the light source device 50 .
  • the control device 11 , the signal processor 20 , and the light source device driver 60 are configured as, for example, semiconductor integrated circuits (ICs).
  • the control device 11 , the signal processor 20 , and the light source device driver 60 may be integrated into one semiconductor integrated circuit (IC), or may be individually configured as semiconductor integrated circuits (ICs) different from one another.
  • the present invention is not limited by the configuration of the control device 11 , the signal processor 20 , and the light source device driver 60 .
  • the signal processor 20 is an arithmetic processor that controls operations of the image display panel 30 and the light source device 50 .
  • the signal processor 20 is coupled to the image display panel driver 40 for driving the image display panel 30 and the light source device driver 60 for driving the light source device 50 .
  • the signal processor 20 performs arithmetic processing on the basis of, for example, the signals received from the control device 11 to generate the processed signal AD and the light source drive signal BL.
  • the signal processor 20 converts the unprocessed signal BD into the processed signal AD.
  • the unprocessed signal BD is a signal for outputting an image reproduced, for example, in a first color, a second color, and a third color.
  • the processed signal AD is a signal for outputting an image reproduced in the first color, the second color, the third color, and a fourth color on the image display panel 30 .
  • the signal processor 20 thus generates the processed signal AD.
  • the signal processor 20 outputs the generated processed signal AD to the image display panel driver 40 .
  • the signal processor 20 generates the light source drive signal BL on the basis of the unprocessed signal BD and the control data OD.
  • the light source drive signal BL is a signal for controlling the quantity of light from the light source device 50 illuminating the image display panel 30 that operates in accordance with the processed signal AD.
  • the signal processor 20 outputs the light source drive signal BL to the light source device driver 60 .
  • the unprocessed signal BD is, for example, an RGB signal.
  • the processed signal AD is, for example, an RGBW signal.
  • the control data OD includes, for example, data indicating segment areas and subsegment areas (to be described later) and signals for control, such as a
  • FIG. 1 illustrates an example in which the pixels 48 are arranged in a matrix (row-column configuration) in a two-dimensional XY-coordinate system on a display surface of the image display panel 30 serving as the display area.
  • the row direction corresponds to the X-direction
  • the column direction corresponds to the Y-direction.
  • each of the pixels 48 includes a first sub-pixel 49 R, a second sub-pixel 49 G, a third sub-pixel 49 B, and a fourth sub-pixel 49 W.
  • the first sub-pixel 49 R displays a first primary color (for example, red).
  • the second sub-pixel 49 G displays a second primary color (for example, green).
  • the third sub-pixel 49 B displays a third primary color (for example, blue).
  • the fourth sub-pixel 49 W displays a fourth color (specifically, white).
  • each of the pixels 48 arranged in a row-column configuration in the image display panel 30 includes the first sub-pixel 49 R that displays the first color, the second sub-pixel 49 G that displays the second color, the third sub-pixel 49 B that displays the third color, and the fourth sub-pixel 49 W that displays the fourth color.
  • the first color, the second color, the third color, and the fourth color are not limited to the first primary color, the second primary color, the third primary color, and white, but only need to be different colors from one another, such as complementary colors.
  • the fourth sub-pixel 49 W that displays the fourth color is preferably brighter than the first sub-pixel 49 R that displays the first color, the second sub-pixel 49 G that displays the second color, and the third sub-pixel 49 B that displays the third color, when irradiated with the same light source lighting amount.
  • the first sub-pixel 49 R, the second sub-pixel 49 G, the third sub-pixel 49 B, and the fourth sub-pixel 49 W will be each called a sub-pixel 49 when they need not to be distinguished from one another.
  • the display device 10 is more specifically a transmissive color liquid crystal display device.
  • the image display panel 30 is a color liquid crystal display panel in which a first color filter for transmitting the first primary color is disposed between the first sub-pixel 49 R and an image viewer, a second color filter for transmitting the second primary color is disposed between the second sub-pixel 49 G and the image viewer, and a third color filter for transmitting the third primary color is disposed between the third sub-pixel 49 B and the image viewer.
  • the image display panel 30 has no color filter disposed between the fourth sub-pixel 49 W and the image viewer. In this case, a large gap is formed on the fourth sub-pixel 49 W. Because of this, a transparent resin layer instead of the color filter may be provided on the fourth sub-pixel 49 W. This can keep the large gap from being formed on the fourth sub-pixel 49 W.
  • the image display panel driver 40 illustrated in FIGS. 1 and 2 is included in a controller of the present embodiment, and includes a signal output circuit 41 and a scanning circuit 42 .
  • the image display panel driver 40 uses the signal output circuit 41 to hold video signals and sequentially output them to the image display panel 30 .
  • the signal output circuit 41 is electrically coupled to the image display panel 30 through signal lines DTL.
  • the image display panel driver 40 uses the scanning circuit 42 to select the sub-pixel 49 in the image display panel 30 and to control on and off of a switching element (such as a thin-film transistor (TFT)) for controlling operations (light transmittance) of the sub-pixel 49 .
  • the scanning circuit 42 is electrically coupled to the image display panel 30 through scanning lines SCL.
  • the light source device 50 illuminates the image display panel with a plurality of light sources.
  • the light source device 50 is disposed on the back side of the image display panel 30 , and emits light toward the image display panel 30 to illuminate the image display panel 30 .
  • the light source device driver 60 controls, for example, the light quantity of the light output from the light source device 50 .
  • the light source device driver 60 is included in the controller of the present embodiment. Specifically, the light source device driver 60 sets the light quantity (intensity of light) of light for irradiating the image display panel 30 to a light quantity corresponding to the light source drive signal BL output from the signal processor 20 by adjusting a value of current supplied to the light source device 50 on the basis of the light source drive signal BL.
  • FIG. 3 is a schematic diagram illustrating a configuration example of the light source device 50 .
  • the light source device 50 has a plurality of light source columns in which a plurality of light sources (such as light sources 51 ) are arranged along one direction.
  • the term “one direction” as used herein refers to at least one of the X-direction and the Y-direction.
  • the light source device 50 of the present embodiment has the light source columns and light source rows in which a plurality of light sources are arranged along two directions of the X-direction and the Y-direction.
  • the light source device 50 has the light sources 51 arranged in a two-dimensional matrix (in a row-column configuration).
  • the light sources 51 are, for example, light-emitting diodes (LEDs) of the same color (such as white).
  • FIG. 3 illustrates the light source device 50 in which seven light sources 51 are arranged along the X-direction, and four light sources 51 are arranged along the Y-direction. This is, however, a mere schematic illustration. The arrangement and the number of the light sources 51 included in the light source device 50 are not limited to the example illustrated in FIG. 3 , but can be changed as appropriate.
  • FIG. 4 is a diagram illustrating an exemplary relation between luminance of each of the light sources 51 arranged along a row direction and a luminance distribution of the entire light source row.
  • Each of the light sources 51 can be changed in luminance within a range from a first upper limit luminance (MAX) to the minimum luminance (LIGHT-OFF) set in advance.
  • the light source 51 illuminates adjacent blocks with part of the light when the light is on. That is, the luminance of each block is affected by the light from the light source 51 disposed in the block and the light from light sources 51 disposed in the adjacent blocks. For example, if all the light sources 51 are lit up at the first upper limit luminance, the luminance of each block has full light luminance (100% ALL) higher than the first upper limit luminance.
  • the light source 51 has a performance to be lit up at luminance higher than the first upper limit luminance.
  • the light source 51 in the present embodiment has a performance to be lit up in a state of increasing the luminance to a second upper limit luminance (LIMIT) higher than the first upper limit luminance.
  • LIMIT second upper limit luminance
  • the first upper limit luminance (MAX) as the luminance of the light source 51 when the amount of current is 100 [%]
  • the second upper limit luminance (LIMIT) is the luminance of the light source 51 when the amount of current is 125 [%].
  • limiting the luminance of the light source 51 when lit up to the first upper limit luminance brings about advantages, such as a reduction in power consumption and an increase in lifetime of the light source 51 . That is, the first upper limit luminance is set in advance as luminance lower than the second upper limit luminance in order to reduce a load on the light source 51 to a level lower than that at the second upper limit luminance.
  • FIG. 4 illustrates the relation between the luminance of each of the light sources 51 arranged along the row direction and the luminance distribution of the entire light source row. The same applies to the relation between the luminance of each of the light sources 51 arranged along the column direction and the luminance distribution of the entire light source column.
  • the relation between the lighting amount and the luminance is also two-dimensional. That is, a light source 51 of a certain block is affected by other light sources 51 in blocks two-dimensionally adjacent to the certain block.
  • FIGS. 5 to 9 are graphs schematically illustrating a flow of determination processing of the lighting amounts of the light sources 51 on the basis of the luminance distribution of the light source device 50 .
  • FIGS. 5 to 9 simplify the explanation by illustrating the relation between the luminance of each of the light sources 51 arranged along the row direction and the light quantity of the entire light source row. In the case of the present embodiment, however, the relation between the lighting amount and the luminance is two-dimensional.
  • the signal processor 20 obtains required luminance on a block-by-block basis.
  • the signal processor 20 determines the required luminance according to a display output image to be displayed on the image display panel 30 illuminated by the light source arranged in each block, more specifically, according to a display output image to be displayed on a segment area-by-segment area basis (to be described later), for example.
  • a symbol La is assigned to the required luminance.
  • the signal processor 20 temporarily sets the lighting amounts of the light sources 51 on a block-by-block basis according to the required luminance. Specifically, the signal processor 20 temporarily sets the lighting amounts of the light sources 51 so that the peak luminance of each of the light sources 51 is substantially equal to the required luminance, for example.
  • the signal processor 20 temporarily sets the lighting amounts of the light sources 51 so that the peak luminance of each of the light sources 51 is substantially equal to the required luminance, for example.
  • the signal processor 20 calculates a temporary lighting amount luminance distribution corresponding to the temporarily set lighting amounts of the light sources 51 .
  • the signal processor 20 compares the temporarily set lighting amounts of the light sources 51 with data (such as reference data 22 f to be described later) indicating various determining factors in calculation of the luminance distribution, and thus calculates the luminance distribution comprehensively given to the display area by the light sources 51 .
  • the various determining factors include a relation (bright/dark) between the lighting amount of each of the light sources 51 and the light quantity obtained in the display area, and influences between adjacent light sources 51 .
  • the relation (bright/dark) between the lighting amount of each of the light sources 51 and the light quantity obtained in the display area can be obtained in advance by, for example, preliminary measurement.
  • a symbol Lc is assigned to the temporary lighting amount luminance distribution corresponding to the temporarily set lighting amounts of the light sources 51 .
  • the signal processor 20 performs correction of the lighting amount of the light source 51 (light source lighting amount correction) for obtaining the required luminance on the basis of a difference between the required luminance and the temporary lighting amount luminance distribution. Specifically, the signal processor 20 performs the correction of the lighting amount so as to increase the lighting amount of the light source 51 of a block where the required luminance not included in the temporary lighting amount luminance distribution occurs. The required luminance in some part is not included in the temporary lighting amount luminance distribution.
  • the correction of the lighting amount of the light source 51 of the block where the required luminance not included in the temporary lighting amount luminance distribution occurs is performed within the range up to the second upper limit luminance (LIMIT).
  • the signal processor 20 calculates a luminance distribution corresponding to the lighting amount after being corrected, in the same scheme as that of the calculation of the temporary lighting amount luminance distribution.
  • the required luminance of the block may not be included in the luminance distribution after being corrected, even after the lighting amount of the light source 51 of the block where the required luminance not included in the temporary lighting amount luminance distribution occurs is increased to the second upper limit luminance (LIMIT).
  • the signal processor 20 performs adjacent light source lighting amount correction to ensure the required luminance by increasing the lighting amount of the light source 51 of a block adjacent to the block.
  • FIG. 10 is a diagram schematically explaining the method for selecting the light sources 51 to be changed in lighting amount.
  • the light source 51 to be changed in lighting amount is selected according to the location of the subsegment area in which the lighting amount for the output produced therein needs to be supplemented, and then the light quantity is supplemented from the periphery by changing the lighting amount of the selected light source 51 .
  • Such selection of the light sources 51 can be employed in the adjacent light source lighting amount correction, and can also be employed in resetting of the temporarily set lighting amounts.
  • FIG. 11 is a graph illustrating an example of resetting of the temporary setting.
  • the signal processor 20 After temporarily setting the lighting amounts of the light sources 51 (refer to FIG. 6 ), the signal processor 20 resets the temporary setting such that, among the lighting amounts temporarily set before performing the correction of the lighting amount (refer to FIG. 8 ) for increasing the lighting amount of the light source 51 of the block where the required luminance not included in the temporary lighting amount luminance distribution occurs, the lighting amount of a block adjacent to a block required to have higher luminance is increased as illustrated in FIG. 11 .
  • FIG. 12 is a functional block diagram illustrating a functional configuration example of the signal processor 20 .
  • the signal processor 20 serves as a block required luminance calculator 21 , a lighting amount calculator 22 , a luminance distribution calculator 23 , and a pixel processor 24 .
  • the block required luminance calculator 21 calculates required luminance, that is luminance required for each of the segment areas and the subsegment areas on the basis of the unprocessed signal BD. This required luminance corresponds to the required luminance described using FIG. 5 explained above.
  • FIG. 14 is a schematic diagram illustrating an example of luminance required for the segment areas.
  • a numerical value illustrated in a rectangle representing the segment area indicates the required luminance for the segment area (to be described later).
  • each of the rectangles sectioned by solid lines represents the segment area.
  • the segment area is a part of the display area in which the image display panel 30 performs the display output of an image.
  • the display area can be divided into a plurality of segment areas. In other words, an area obtained by combining all the segment areas serves as the display area.
  • Each of the pixels 48 included in the image display panel 30 is included in any of the segment areas.
  • the segment areas are arranged along at least one direction.
  • the segment areas are arranged along two orthogonal or intersecting directions.
  • the block required luminance calculator 21 sets the segment areas on the basis of the control data OD.
  • the light source 51 is individually provided in each of the segment areas. In this manner, each of the light sources 51 is assigned to a corresponding one of the segment areas. Each of the segment areas is illuminated by one or more of the light sources.
  • FIG. 15 is a schematic diagram illustrating an example of luminance required for the respective subsegment areas.
  • dashed lines represent dividing lines that divide the segment area into a plurality of subsegment areas.
  • a numerical value illustrated in a rectangle representing the subsegment area indicates the required luminance for the subsegment area (to be described later).
  • the subsegment area is a part of the segment area.
  • One segment area can be divided into a plurality of subsegment areas.
  • One subsegment area is an area including one or more of the pixels 48 .
  • each of the segment areas includes four subsegment areas defined by two dividing lines, one of which halves the segment area in one of two orthogonal directions, the other of which halves the segment area in the other of the two orthogonal directions.
  • one of the two dividing lines extends along the X-direction, and the other thereof extends along the Y-direction.
  • the four subsegment areas included in one segment area are arranged in the X-direction and the Y-direction as 2 ⁇ 2 parts.
  • FIG. 15 illustrates an example in which the two dividing lines divide the segment area into four equal parts. This is, however, a mere example, and the present invention is not limited thereto.
  • the numbers of pixels 48 in the X-direction included in one segment area may differ from one another.
  • the numbers of pixels 48 in the Y-direction included in one segment area may differ from one another.
  • the block required luminance calculator 21 calculates the luminance required for the subsegment area. Specifically, the block required luminance calculator 21 calculates values of the required luminance according to gradation values of the sub-pixels 49 represented by the unprocessed signal BD. As an example, a case will be described where the unprocessed signal BD represents each color of the sub-pixels 49 as an 8-bit gradation value.
  • the 8-bit gradation value can be expressed as a numerical value ranging from 0 as the minimum value to 255 as the maximum value.
  • the luminance required for the light source 51 for illuminating the sub-pixel 49 is assumed to be the first upper limit luminance.
  • the required luminance in this case is 100 [%].
  • the luminance required for the light source 51 for illuminating the sub-pixel 49 is assumed to be the minimum luminance.
  • the required luminance in this case is 0 [%], which means a light-off state of the light source 51 .
  • the required luminance is 100 [%]
  • the full light luminance (100% ALL) is required.
  • the block required luminance calculator 21 calculates the required luminance within the limit of the full light luminance (100% ALL) that is lower than the second upper limit luminance (LIMIT).
  • the block required luminance calculator 21 calculates the required luminance corresponding to the gradation value of the sub-pixel 49 represented by the unprocessed signal BD. For example, the block required luminance calculator 21 calculates the required luminance of the sub-pixel 49 having a gradation value (such as 127) at the center between the maximum value and the minimum value to be 50 [%].
  • the relation between the gradation value and the required luminance may be defined by predetermined data (such as data in a table format) stored in a storage device included in the block required luminance calculator 21 , or may be calculated using a predetermined algorithm implemented in the block required luminance calculator 21 .
  • the block required luminance calculator 21 calculates the required luminance values corresponding to the gradation values of all the sub-pixels 49 .
  • the block required luminance calculator 21 determines the highest required luminance among the calculated required luminance values of the sub-pixels 49 included in one subsegment area as the required luminance of the one subsegment area.
  • the block required luminance calculator 21 individually determines the required luminance for each of the subsegment areas.
  • a numerical value illustrated in a rectangle representing a subsegment area indicates the required luminance of the subsegment area.
  • the block required luminance calculator 21 temporarily sets luminance values of the respective segment areas for determining the lighting amounts of the light sources 51 on the basis of the maximum luminance among the luminance values required for the respective subsegment areas included in each of the segment areas. Specifically, the block required luminance calculator 21 sets the highest required luminance among the calculated required luminance values of the subsegment areas included in one subsegment area as the required luminance of the one segment area. The block required luminance calculator 21 individually sets the required luminance for each of the segment areas. The block required luminance calculator 21 outputs, to the lighting amount calculator 22 , temporary setting information BB indicating the required luminance of all the segment areas for which the temporary setting has been made. In FIG. 14 , a numerical value illustrated in a rectangle representing a segment area indicates the required luminance of the segment area.
  • FIG. 13 is a subblock diagram of the lighting amount calculator 22 .
  • the lighting amount calculator 22 outputs the light source drive signal BL on the basis of the required luminance indicated by the temporary setting information BB.
  • the lighting amount calculator 22 includes, for example, a temporary lighting amount setter 22 a , a temporary lighting amount resetter 22 b , a temporary lighting amount luminance distribution calculator 22 c , a lighting amount corrector 22 d , an adjacent light source lighting amount corrector 22 e , and the reference data 22 f.
  • the temporary lighting amount setter 22 a temporarily sets the lighting amounts of the light sources 51 corresponding to the required luminance (light source lighting amount temporary setting).
  • the lighting amounts temporarily set by the temporary lighting amount setter 22 a correspond to the lighting amounts set through the temporary setting described above with reference to FIG. 6 .
  • the temporary lighting amount setter 22 a temporarily sets the lighting amounts of the respective light sources 51 so that, for example, the peak luminance of each of the light sources 51 arranged at locations corresponding to the respective segment areas is substantially equal to the required luminance of the corresponding one of the segment areas.
  • the temporary lighting amount resetter 22 b calculates reset luminance from the luminance required for the subsegment areas. Specifically, the temporary lighting amount resetter 22 b calculates the reset luminance, for example, by multiplying the required luminance of each of the subsegment areas by a predetermined coefficient (such as k1 or k2) for calculating the reset luminance.
  • the lighting amounts corresponding to the luminance reset by the temporary lighting amount resetter 22 b correspond to the lighting amounts set through the resetting described above with reference to FIG. 11 .
  • FIG. 16 is a schematic diagram illustrating a calculation example of the required luminance of other segment areas based on the luminance required for the respective subsegment areas included in one segment area.
  • the present embodiment individually sets a first coefficient (k1) and a second coefficient (k2).
  • the first coefficient (k1) is a coefficient for calculating the reset luminance of segment areas adjacent to a subsegment area in the X-direction and the Y-direction
  • the second coefficient (k2) is a coefficient for calculating the reset luminance of a segment area adjacent to the subsegment area in an oblique direction different from the X-direction and the Y-direction.
  • the first coefficient (k1) is a unique numerical value (such as 0.5) set within the range of, for example, 0.4 to 0.6
  • the second coefficient (k2) is a unique numerical value (such as 0) set within the range of, for example, 0 to 0.25.
  • the numerical value ranges and the unique numerical values of these coefficients are mere examples, and are not limited thereto, and can be changed as appropriate.
  • the reset luminance (50 [%]) is calculated by multiplying the required luminance by the first coefficient (k1) as the reset luminance of each of these segment areas.
  • the reset luminance (0 [%]) is calculated by multiplying the required luminance by the second coefficient (k2) as the reset luminance of this segment area.
  • the reset luminance (25 [%]) is calculated by multiplying the required luminance by the first coefficient (k1) as the reset luminance of each of these segment areas.
  • the reset luminance (0 [%]) is calculated by multiplying the required luminance by the second coefficient (k2) as the reset luminance of each of these segment areas.
  • the coefficients for calculating the reset luminance may be set on the basis of the reference data 22 f stored in a storage device included in the lighting amount calculator 22 , or may be included in an algorithm implemented in the temporary lighting amount resetter 22 b .
  • the first and second coefficients in the present embodiment need not be individual coefficients, but may be unified into one coefficient. The calculation of the reset luminance using the second coefficient may be omitted.
  • the above description has exemplified the processing in the case of calculating the reset luminance values from the values of the required luminance of a plurality of subsegment areas included in one segment area.
  • the temporary lighting amount resetter 22 b sequentially or concurrently executes the same processing for all the segment areas.
  • the temporary lighting amount resetter 22 b has completed the calculation of the reset luminance from the required luminance values of all the subsegment areas included in all the segment areas, the lighting amounts of the segment areas temporarily set by the temporary lighting amount setter 22 a are separately kept.
  • the temporary lighting amount resetter 22 b calculates a plurality of values of reset luminance for one segment area.
  • a plurality of values of reset luminance calculated from the values of the required luminance of a plurality of subsegment areas sharing an adjacent segment area serve as the values of reset luminance for the segment area.
  • the temporary lighting amount resetter 22 b calculates the reset luminance from the required luminance of a plurality of subsegment areas included in the corresponding segment area. Consequently, the number of values of reset luminance calculated for one segment area can exceed the number of values of reset luminance calculated from a plurality of subsegment areas included in one segment area. If a plurality of values of reset luminance is calculated for one segment area, the temporary lighting amount resetter 22 b determines the highest value of the reset luminance as the reset luminance for the segment area.
  • the temporary lighting amount resetter 22 b resets the luminance of a segment area where the calculated reset luminance is higher than the luminance having been set for the the segment area (refer to FIG. 14 ) to the reset luminance (refer to FIG. 17 ).
  • the temporary lighting amount resetter 22 b resets the luminance of segment areas adjacent to the subsegment areas (adjacent light source lighting amount reset). For segment areas for which the luminance has not been reset, the luminance of the segment areas is kept at the luminance corresponding to the lighting amounts temporarily set by the temporary lighting amount setter 22 a , that is, at the required luminance calculated by the block required luminance calculator 21 .
  • the temporary lighting amount luminance distribution calculator 22 c calculates the temporary lighting amount luminance distribution according to the lighting amounts in which the luminance after being reset by the temporary lighting amount resetter 22 b is reflected.
  • the temporary lighting amount luminance distribution calculated by the temporary lighting amount luminance distribution calculator 22 c corresponds to the temporary lighting amount luminance distribution described above with reference to FIG. 7 .
  • the temporary lighting amount luminance distribution calculator 22 c obtains, for example, the lighting amounts of the respective light sources 51 corresponding to the luminance after being reset, compares these lighting amounts with the reference data 22 f , and calculates the luminance distribution comprehensively given to the display area by the light sources 51 as the temporary lighting amount luminance distribution.
  • the reference date 22 f indicates the various determining factors in the calculation of the luminance distribution.
  • the examples of the various determining factors include the relation (bright/dark) obtained in advance by, for example, preliminary measurement between the lighting amount of each of the light sources 51 and the light quantity obtained in the display area.
  • the examples of the various determining factors also include influences between adjacent light sources 51 .
  • the lighting amount calculator 22 If the required luminance values have been obtained for all the segment areas by the time when the temporary lighting amount luminance distribution is calculated, the lighting amount calculator 22 outputs the light source drive signal BL for lighting up the light sources 51 at lighting amounts corresponding to the luminance after being reset by the temporary lighting amount resetter 22 b.
  • the lighting amount corrector 22 d performs the correction of the lighting amounts of the light sources 51 (light source lighting amount correction) for obtaining the required luminance on the basis of the difference between the required luminance and the temporary lighting amount luminance distribution.
  • the light source lighting amount correction performed by the lighting amount corrector 22 d corresponds to the light source lighting amount correction described above with reference to FIG. 8 .
  • the lighting amount corrector 22 d of the present embodiment corrects the lighting amounts of the light sources within a range equal to or lower than the second upper limit luminance (such as LIMIT).
  • the lighting amount corrector 22 d of the present embodiment corrects the lighting amount of the light source illuminating the segment area.
  • the lighting amount corrector 22 d sets a representative point in the segment area for which the required luminance has not been obtained in the temporary lighting amount luminance distribution.
  • the term “representative point” refers to luminance corresponding to a gradation value of one pixel 48 in a subsegment area with the required luminance of the maximum luminance among a plurality of subsegment areas included in one segment area.
  • the pixel 48 with the gradation value employed as the representative point may be a pixel 48 exhibiting the highest gradation value in this subsegment area, or may be a pixel 48 extracted by sampling.
  • the lighting amount corrector 22 d calculates luminance required for performing display output of the representative point that has been set.
  • the lighting amount corrector 22 d acquires the luminance (current luminance) of the segment area for which the representative point has been set among values of luminance of a plurality of segment areas indicated by the temporary lighting amount luminance distribution.
  • the lighting amount corrector 22 d calculates the difference between the luminance required for performing display output of the representative point and the current luminance.
  • the lighting amount corrector 22 d determines whether the difference can be supplemented by correcting the lighting amount of the light source 51 corresponding to this segment area within the upper limit of the second upper limit luminance (LIMIT).
  • the lighting amount corrector 22 d calculates, for example, a luminance distribution that can be obtained by correcting the lighting amount of the light source 51 corresponding to this segment area to a lighting amount equal to or lower than the second upper limit luminance (LIMIT) using the same method as that used by the temporary lighting amount luminance distribution calculator 22 c to calculate the temporary lighting amount luminance distribution, and determines whether the required luminance of this segment area can be obtained by using the calculated luminance distribution. If the required luminance of this segment area is determined to be obtainable, the lighting amount corrector 22 d corrects the lighting amount of the light source 51 corresponding to this segment area to the lowest lighting amount with which the required luminance of this segment area can be obtained.
  • LIMIT second upper limit luminance
  • the lighting amount corrector 22 d sets the lighting amount of the light source 51 corresponding to this segment area to the second upper limit luminance (LIMIT), and outputs reference information to the adjacent light source lighting amount corrector 22 e .
  • the reference information includes information indicating an amount of luminance by which the lighting amount of the light source 51 corresponding to this segment area is still insufficient even after being set to the second upper limit luminance (LIMIT), information indicating the position of the segment area where the lighting amount is insufficient, and information indicating the position of a subsegment area exhibiting the maximum luminance in this segment area.
  • the lighting amount calculator 22 When the required luminance become obtainable for all the segment areas as a result of the light source lighting amount correction, the lighting amount calculator 22 outputs the light source drive signal BL for lighting up the light sources 51 at lighting amounts corresponding to the luminance after being corrected by the lighting amount corrector 22 d.
  • the adjacent light source lighting amount corrector 22 e performs the adjacent light source lighting amount correction.
  • the adjacent light source lighting amount correction performed by the adjacent light source lighting amount corrector 22 e corresponds to the adjacent light source lighting amount correction described above with reference to FIG. 9 .
  • the adjacent light source lighting amount corrector 22 e determines the light source 51 to be increased in lighting amount for supplementing the insufficiency in lighting amount on the basis of the information indicating the position of the segment area where the lighting amount is insufficient and the information indicating the position of the subsegment area exhibiting the maximum luminance in this segment area among pieces of information included in the reference information.
  • the adjacent light source lighting amount corrector 22 e increases the luminance set for the segment area adjacent to the subsegment area exhibiting the maximum luminance. If a plurality of such segment areas are adjacent to the subsegment area, the adjacent light source lighting amount corrector 22 e determines segment areas to be increased in luminance according to a predetermined order of priority. The information indicating the order of priority is included in, for example, the reference data 22 f.
  • FIG. 18 is a diagram illustrating an example of a correspondence relation between the segment area where the luminance is insufficient, the subsegment area exhibiting the maximum luminance in the segment area, and the segment areas corresponding to the positions of the light sources to be subjected to the adjacent light source lighting amount correction for increasing the lighting amounts in order to supplement the insufficient luminance, and the execution order of the light source lighting amount correction.
  • parenthesized numbers (1), (2), and (3) indicate the order of priority of the segment areas corresponding to the light sources to be subjected to the adjacent light source lighting amount correction.
  • the adjacent light source lighting amount corrector 22 e selects, from among the light sources 51 corresponding to segment areas adjacent to the subsegment area exhibiting the maximum luminance in the segment area that is still insufficient in luminance after being subjected to the light source lighting amount correction, the light source 51 corresponding to a segment area (1) adjacent to the subsegment area exhibiting the maximum luminance in the X-direction as a light source to be subjected to the adjacent light source lighting amount correction with the highest priority.
  • the adjacent light source lighting amount corrector 22 e determines whether the insufficiency in luminance remaining after the light source lighting amount correction has been performed by the lighting amount corrector 22 d can be supplemented if the lighting amount of the light source 51 corresponding to the segment area (1) is corrected within the upper limit of the second upper limit luminance (LIMIT). Specifically, the adjacent light source lighting amount corrector 22 e calculates, for example, a luminance distribution that can be obtained by correcting the lighting amount of the light source 51 corresponding to this segment area (1) to a lighting amount equal to or lower than the second upper limit luminance (LIMIT), in the same manner as that used by the temporary lighting amount luminance distribution calculator 22 c to calculate the temporary lighting amount luminance distribution.
  • LIMIT second upper limit luminance
  • the adjacent light source lighting amount corrector 22 e determines whether the required luminance of the segment area where the luminance is insufficient can be obtained by using the calculated luminance distribution. If the required luminance of the segment area is determined to be obtainable, the adjacent light source lighting amount corrector 22 e corrects the lighting amount of the light source 51 corresponding to this segment area (1) to the lowest lighting amount with which the required luminance of the segment area where the luminance is insufficient can be obtained.
  • the adjacent light source lighting amount corrector 22 e sets the lighting amount of the light source 51 corresponding to this segment area (1) to the second upper limit luminance (LIMIT), and selects, from among the light sources 51 corresponding to segment areas adjacent to the subsegment area exhibiting the maximum luminance in the segment area that is still insufficient in luminance after being subjected to the light source lighting amount correction, the light source 51 corresponding to a segment area (2) adjacent thereto in the Y-direction as a light source to be subjected to the adjacent light source lighting amount correction with the next priority.
  • LIMIT second upper limit luminance
  • the adjacent light source lighting amount corrector 22 e determines whether the insufficiency in luminance remaining after the light source lighting amount correction has been performed by the lighting amount corrector 22 d can be supplemented if the lighting amount of the light source 51 corresponding to the segment area (2) is corrected within the upper limit of the second upper limit luminance (LIMIT). If the insufficiency in luminance is determined to be supplementable, the adjacent light source lighting amount corrector 22 e performs the same processing as that of the segment area (1) described above.
  • the adjacent light source lighting amount corrector 22 e sets the lighting amount of the light source 51 corresponding to this segment area (2) to the second upper limit luminance (LIMIT), and selects, from among the light sources 51 corresponding to segment areas adjacent to the subsegment area exhibiting the maximum luminance in the segment area that is still insufficient in luminance after being subjected to the light source lighting amount correction, the light source 51 corresponding to a segment area (3) adjacent thereto in an oblique direction as a light source to be subjected to the adjacent light source lighting amount correction with the next priority. Subsequently, the adjacent light source lighting amount corrector 22 e performs the same processing as in the cases of the segment areas (1) and (2) on the segment area (3).
  • LIMIT second upper limit luminance
  • FIG. 18 and FIG. 24 to be described later illustrate the priority numbers (1) to (3) indicating the priority order of the segment areas to be subjected to the adjacent light source lighting amount correction.
  • priority numbers (4) and more may be set in advance. In this case, if the insufficiency in luminance is still not supplementable after the segment area (3) is subjected to the adjacent light source lighting amount correction, the same processing as that of (1) to (3) may be performed on segment areas (4) and later.
  • FIG. 19 is a schematic diagram illustrating an example of the luminance of the segment areas after being subjected to the adjacent light source lighting amount correction.
  • the luminance of the segment area subjected to the adjacent light source lighting amount correction is a mere example, and is not limited thereto.
  • the lighting amount calculator 22 outputs the light source drive signal BL for lighting up the light sources 51 at lighting amounts corresponding to the luminance after being corrected by the adjacent light source lighting amount corrector 22 e .
  • the signal processor 20 having the function as the lighting amount calculator 22 serves as the controller that outputs the light source drive signal BL on the basis of the image signal.
  • the lighting amount corrector 22 d may set the representative point not only in the subsegment area with the required luminance of the maximum luminance, but also in each of all the subsegment areas, and may perform the same light source lighting amount correction as that described above on all subsegment areas in one segment area.
  • the adjacent light source lighting amount corrector 22 e supplements the insufficiency in luminance as a result of the correction performed by the lighting amount corrector 22 d on all the subsegment areas in one segment area.
  • FIG. 18 illustrates the execution order of the light source lighting amount correction in the case where the representative point is set not only in the subsegment area with the required luminance of the maximum luminance, but also in each of all the subsegment areas, and where the same processing as that described above is performed on all subsegment areas in one segment area.
  • the execution order of the light source lighting amount correction in the case of setting the representative points in all the subsegment areas is determined in advance.
  • the lighting amount corrector 22 d defines in advance a variable (z) for managing the calculation order to be a certain initial value (such as zero), and performs the light source lighting amount correction using the representative points that have been set.
  • the lighting amount corrector 22 d increments the variable (z) by one, and performs the light source lighting amount correction using a representative point in a subsegment area corresponding to the value set as the variable.
  • the repetition of the increment of the variable (z) and the light source lighting amount correction ends when the light source lighting amount correction is completed after the value of the variable (z) has reached a certain final value (such as three).
  • the luminance distribution calculator 23 calculates the luminance distribution of the entire light source device 50 caused by the lighting amounts of the light sources 51 indicated by the light source drive signal BL. Specifically, the luminance distribution calculator 23 obtains the luminance distribution using, for example, the same data as the reference data stored in advance in a storage device included in the luminance distribution calculator 23 or an algorithm already implemented in the luminance distribution calculator 23 .
  • the luminance distribution calculator 23 may be configured to be capable of referring to the reference data 22 f of the lighting amount calculator 22 .
  • the reference data 22 f may be provided so as to be referable from all the functions included in the signal processor 20 .
  • the luminance distribution calculator 23 outputs luminance distribution information BM indicating the luminance distribution to the pixel processor 24 .
  • the pixel processor 24 obtains the gradation value of each of the pixels 48 for performing the display output on the basis of the unprocessed signal BD with the luminance distribution indicated by the luminance distribution information BM. Specifically, for example, in a segment area for which the luminance has been reset by the temporary lighting amount resetter 22 b , the light from the light source device 50 is more intense than the luminance before being reset by the block required luminance calculator 21 . As a result, the pixel 48 is sometimes made brighter than necessary if the transmittance of the pixel 48 is controlled while maintaining the gradation value indicated by the processed signal AD.
  • the pixel processor 24 corrects the gradation value of each of the sub-pixels 49 constituting the pixels 48 included in the segment area that has been reset in luminance.
  • FIG. 20 is a conceptual diagram of an extended HSV color space reproducible by the display device of the embodiment.
  • the pixel 48 since the pixel 48 includes the fourth sub-pixel 49 W, a color space extended from a color space of the unprocessed signal BD can be employed to obtain the processed signal AD.
  • the extended HSV color space with the fourth color has a shape obtained by placing a color space having a substantially truncated cone shape on a cylindrical HSV color space. In the color space having a substantially truncated cone shape, the maximum value of a value (also called brightness) V is reduced as saturation S increases.
  • a value also called brightness
  • the cylindrical HSV color space is a color space that can be displayed by the first sub-pixel 49 R, the second sub-pixel 49 G, and the third sub-pixel 49 B.
  • the signal processor 20 includes a storage device storing a maximum value Vmax(S) of the brightness using the saturation S as a variable in the extended HSV color space extended by addition of the fourth color. That is, the signal processor 20 stores the maximum value Vmax(S) of the brightness for each pair of coordinates (coordinate values) of the saturation S and hue H regarding the three-dimensional shape of the extended HSV color space illustrated in FIG. 20 .
  • An image signal SRGB is a signal having an image signal value corresponding to the first, second, and third primary colors. Consequently, the extended HSV color space of the image signal SRGB has a cylindrical shape, that is, the same shape as a cylindrical part of the extended HSV color space illustrated in FIG. 20 . Accordingly, a display signal SRGBW can be calculated as an extended image signal obtained by extending the image signal SRGB for the extended HSV color space.
  • the extended image signal is extended by an extension coefficient ⁇ determined by comparing the brightness level in the extended HSV color space. Extending the signal level of the image signal by the extension coefficient ⁇ allows the value of the fourth sub-pixel 49 W to be larger, and thus can increase the luminance of the entire image.
  • the image can be displayed at exactly the same luminance as that of the image signal SRGB by reducing the luminance of the light source device 50 by a factor of 1/ ⁇ to counterbalance the increase in luminance of the entire image by the extension coefficient ⁇ .
  • the block required luminance calculator 21 calculates, as the required luminance, the extension coefficient ⁇ and the luminance of the light source device 50 reduced by the factor of 1/ ⁇ according to the extension coefficient ⁇ . That is, the luminance indicated by the temporary setting information BB may be the required luminance of a segment area corresponding to the luminance of the light source device 50 reduced by the factor of 1/ ⁇ according to the extension coefficient ⁇ .
  • the pixel processor 24 performs the processing to obtain the gradation value of the sub-pixel 49 .
  • ⁇ denote a constant depending on the display device 10
  • X 1 (p,q) serving as a display signal of the first sub-pixel 49 R
  • X 2 (p,q) serving as a display signal of the second sub-pixel 49 G
  • X 3 (p,q) serving as a display signal of the third sub-pixel 49 B transmitted to a (p,q)th pixel (or a set of the first, second, and third sub-pixels 49 R, 49 G, and 49 B)
  • ⁇ will be described later.
  • X 1 (p,q) ⁇ x 1 (p,q) ⁇ X 4 (p,q) (1)
  • X 2 (p,q) ⁇ x 2 (p,q) ⁇ X 4 (p,q) (2)
  • X 3 (p,q) ⁇ x 3 (p,q) ⁇ X 4 (p,q) (3)
  • a display signal value X 4 (p,q) can be obtained on the basis of the product of Min (p,q) and the extension coefficient ⁇ .
  • Min (p,q) is the minimum value of the image signal values x 1 (p,q) , x 2 (p,q) , and x 3 (p,q) .
  • the display signal value X 4 (p,q) can be obtained on the basis of Expression (4) below.
  • Expression (4) the product of Min (p,q) and the extension coefficient ⁇ is divided by ⁇ .
  • the present invention is, however, not limited thereto.
  • the extension coefficient ⁇ is determined for each image display frame.
  • X 4 (p,q) Min (p,q) ⁇ / ⁇ (4)
  • the saturation S (p,q) and the brightness V(S) (p,q) in the cylindrical HSV color space can be obtained from Expressions (5) and (6) below on the basis of the image signal SRGB including the image signal value x 1 (p,q) for the first primary color, the image signal value x 2 (p,q) for the second primary color, and the image signal value x 3 (p,q) for the third primary color.
  • S (p,q) (Max (p,q) ⁇ Min (p,q) )/Max (p,q) (5)
  • V ( S ) (p,q) Max (p,q) (6)
  • Max (p,q) is the maximum value of the image signal values x 1 (p,q) , x 2 (p,q) , and x 3 (p,q) of the image signal SRGB.
  • Min (p,q) is the minimum value of input values of the three sub-pixels.
  • the saturation S can be a value ranging from 0 to 1
  • the brightness V(S) can be a value ranging from 0 to (2 n ⁇ 1), where n is the number of display gradation bits.
  • the fourth sub-pixel 49 W for displaying the fourth color is brighter than the first sub-pixel 49 R for displaying the first primary color, the second sub-pixel 49 G for displaying the second primary color, and the third sub-pixel 49 B for displaying the third primary color when irradiated with the same lighting amount.
  • the thus obtained maximum value Vmax(S) of the brightness using the saturation S as a variable in the extended HSV color space extended by adding the fourth color is stored in the signal processor 20 as a kind of look-up table, for example.
  • the signal processor 20 determines the maximum value Vmax(S) of the brightness using the saturation S as a variable in the extended HSV color space as occasion demands.
  • the extension coefficient ⁇ is determined, for example, on the basis of ⁇ (S) obtained for the pixels 48 .
  • the extension calculation is performed so as to keep a ratio between the luminance of the first primary color displayed by (first sub-pixel 49 R+fourth sub-pixel 49 W), the luminance of the second primary color displayed by (second sub-pixel 49 G+fourth sub-pixel 49 W), and the luminance of the third primary color displayed by (third sub-pixel 49 B+fourth sub-pixel 49 W).
  • the calculation is performed so as to also keep (maintain) color tone.
  • the calculation is performed so as to keep (maintain) a gradation-luminance characteristic (gamma ( ⁇ ) characteristic). If all the image signal values for any one of the pixels 48 or any group of the pixels 48 are zero or small, the extension coefficient ⁇ may be calculated without including such a pixel 48 or such a group of pixels 48 .
  • the signal processor 20 may, for example, calculate the extension coefficient ⁇ for each pixel and determine the extension coefficient ⁇ for any area on the basis of at least one of the extension coefficients ⁇ calculated for pixels in the area, or may determine the extension coefficient ⁇ for any area on the basis of at least one of the extension coefficients ⁇ of sampled pixels.
  • the area may be one pixel or the entire display surface, or may be, for example, a segment area.
  • Expressions (1), (2), (3), and (4) are used to convert the image signal SRGB into the display signal SRGBW.
  • the luminance of the light source device 50 can be set to the lowest value at which colors can be reproduced in the extended HSV color space of the display device 10 by controlling the division driving of the light source device 50 and controlling the image display to the image display panel 30 using the extension coefficient ⁇ . Due to this, power consumption of the display device 10 can be reduced.
  • FIG. 21 is an exemplary flowchart of processing to obtain the light source drive signal BL.
  • the temporary lighting amount setter 22 a calculates the required luminance of each of the subsegment areas. Subsequently, the temporary lighting amount setter 22 a temporarily sets the luminance of each of the segment areas for determining the lighting amounts of a plurality of light sources on the basis of the maximum luminance among the required luminance values of the respective subsegment areas included in each of the segment areas. Thus, the temporary lighting amount setter 22 a temporarily sets the luminance of the segment area as the light source lighting amount temporary setting (Step S 1 ).
  • the temporary lighting amount resetter 22 b resets the luminance of the segment area to the reset luminance.
  • the temporary lighting amount resetter 22 b resets the luminance of the segment area as the adjacent light source lighting amount reset (Step S 2 ).
  • the temporary lighting amount luminance distribution calculator 22 c calculates the temporary lighting amount luminance distribution corresponding to the lighting amounts in which the luminance after being reset by the temporary lighting amount resetter 22 b is reflected (Step S 3 ).
  • the lighting amount corrector 22 d performs the correction of the lighting amounts of the light sources 51 (light source lighting amount correction) for obtaining the required luminance on the basis of the difference between the required luminance and the temporary lighting amount luminance distribution (Step S 4 ).
  • the adjacent light source lighting amount corrector 22 e performs the adjacent light source lighting amount correction according to the reference information received from the lighting amount corrector 22 d (Step S 5 ).
  • FIG. 22 is an exemplary flowchart of calculation processing of the light source lighting amount correction illustrated in FIG. 21 .
  • FIG. 22 illustrates an exemplary execution routine of the light source lighting amount correction performed on one segment area in the case where the representative point is set not only for the subsegment area with the required luminance of the maximum luminance, but also for each of all the subsegment areas, and where the same light source lighting amount correction as that described above is performed on all subsegment areas in the segment area.
  • Each of the variable (yv), the variable (xh), and the variable (z) is a variable for setting a value of a counter used in the calculation processing of the light source lighting amount correction performed by the lighting amount corrector 22 d .
  • Each of the variable (yv), the variable (xh), and the variable (z) may be a variable managed by using a counter controlled by a logic circuit mounted on the lighting amount corrector 22 d , or by a software program.
  • the segment areas to be reset can be changed with the change in the display output image, and light sources to be corrected for increasing the luminance can be easily dispersed. As a result, the load on the light sources can be further reduced.
  • the high luminance output in the subsegment area with the required luminance of the maximum luminance shifts toward a segment area adjacent to this subsegment area
  • the amount of the change in luminance on a per segment area basis can be reduced, and the display quality is more easily restrained from deteriorating due to the sudden large change in luminance. As a result, the display output can be performed with higher display quality.
  • the lighting amount of the light source illuminating the segment area is corrected within the range equal to or lower than the predetermined second upper limit luminance. Due to this, a light quantity required for the display output can be obtained in a more reliable manner.
  • the luminance of the segment area is reset to reset luminance. Due to this, the difference between the luminance of the subsegment area and the luminance of the segment area adjacent to the subsegment area can be easily reduced. Consequently, in the case where the high luminance output in the subsegment area with the required luminance of the maximum luminance shifts toward the segment area adjacent to this subsegment area, the amount of the change in luminance on a per segment area basis can be reduced, and the display quality is more easily restrained from deteriorating due to the sudden large change in luminance. As a result, the display output can be performed with higher display quality.
  • the segment areas are arranged along at least one direction (for example, along two directions of the X-direction and the Y-direction).
  • the two dividing lines for dividing the segment area into the subsegment areas extend along at least this one direction (for example, along two directions of the X-direction and the Y-direction). Due to this, the parallel arrangement direction of the segment areas and the parallel arrangement direction of the subsegment areas can correspond to each other, and regularity about the resetting of the luminance can be more easily ensured.
  • the light sources are arranged along at least one direction (for example, along two directions of the X-direction and the Y-direction). Due to this, the luminance of the segment areas and the lighting amounts of the light sources 51 can more easily correspond to each other, and the scheme of control of the light sources 51 according to the resetting of the luminance can be made simpler.
  • FIG. 23 is a block diagram illustrating an exemplary configuration of a display device according to the second embodiment.
  • the display device of the second embodiment further includes a switching device 25 in addition to the configuration of the display device of the first embodiment.
  • the switching device 25 is a circuit for switching among multiple patterns of the execution order of the light source lighting amount correction performed by the lighting amount corrector 22 d .
  • the switching device 25 includes, for example, calculation order storage 26 , a timer 27 , and a read-only memory (ROM) 28 .
  • ROM read-only memory
  • the calculation order storage 26 stores the execution order of the light source lighting amount correction to be employed by the lighting amount corrector 22 d . Specifically, in the second embodiment, a plurality (such as two patterns) of such execution order of the light source lighting amount correction are provided.
  • the ROM 28 keeps the patterns of execution orders.
  • the calculation order storage 26 reads from the ROM 28 and stores a pattern of execution order of the light source lighting amount correction to be currently employed by the lighting amount corrector 22 d among the patterns of execution orders.
  • FIG. 24 is a diagram illustrating another example of the correspondence relation between the segment area where the luminance is insufficient, the subsegment area exhibiting the maximum luminance in the segment area, and the segment areas corresponding to the positions of the light sources 51 to be subjected to the adjacent light source lighting amount correction for increasing the lighting amounts in order to supplement the insufficient luminance, and the execution order of the light source lighting amount correction.
  • the ROM 28 stores the execution order of the light source lighting amount correction described with reference to FIG. 18 as one pattern.
  • the ROM 28 stores the execution order of the light source lighting amount correction described with reference to FIG. 24 as another pattern.
  • FIG. 24 is a diagram illustrating another example of the correspondence relation between the segment area where the luminance is insufficient, the subsegment area exhibiting the maximum luminance in the segment area, and the segment areas corresponding to the positions of the light sources 51 to be subjected to the adjacent light source lighting amount correction for increasing the lighting amounts in order to supplement the insufficient luminance, and the execution order of the light source lighting amount
  • Switching the patterns of the execution order may involve switching the orders of priority in which the segment areas are to be subjected to the adjacent light source lighting amount correction, in addition to the execution order of the light source lighting amount correction.
  • the light source 51 corresponding to a segment area (1) adjacent in the Y-direction to the subsegment area exhibiting the maximum luminance in the segment area that is still insufficient in luminance after being subjected to the light source lighting amount correction may be selected as a light source to be subjected to the adjacent light source lighting amount correction with the highest priority from among the light sources 51 corresponding to segment areas adjacent to the subsegment exhibiting the maximum luminance.
  • the light source 51 corresponding to a segment area (2) adjacent to the subsegment area exhibiting the maximum luminance in the X-direction may be selected as a light source to be subjected to the adjacent light source lighting amount correction with the next priority from among the light sources 51 corresponding to segment areas adjacent to the subsegment area exhibiting the maximum luminance.
  • the timer 27 counts time to determine time to switch the execution order of the light source lighting amount correction to another pattern. Specifically, the timer 27 outputs a switching timing signal TD to the calculation order storage 26 each time a predetermined time elapses, the switching timing signal TD being a signal for indicating the time to switch the execution order of the light source lighting amount correction to the other pattern.
  • the control device 11 of the second embodiment outputs a clock signal CS to the switching device 25 at a predetermined period.
  • the calculation order storage 26 checks whether the switching timing signal TD is received in response to input timing of the clock signal CS. If the switching timing signal TD is received, the calculation order storage 26 reads, as an employed pattern RD, a pattern of the execution order of the light source lighting amount correction different from the stored pattern of the execution order of the light source lighting amount correction.
  • the calculation order storage 26 outputs a command signal PL for making the lighting amount corrector 22 d employ the employed pattern RD to the lighting amount calculator 22 .
  • the calculation order storage 26 keeps data indicating the order of employment of the three or more patterns of the execution order, selects and reads from the ROM 28 the execution order of the light source lighting amount correction in the order of employment according to the data, and outputs the command signal PL.
  • the switching device 25 is provided as an independent configuration in FIG. 23 , the function of the switching device 25 may be a function included in another configuration.
  • the signal processor 20 may have the same function as that of the switching device 25 .
  • What is changed by the change in the execution order of the light source lighting amount correction due to the switching of the pattern is not limited to the execution order of the light source lighting amount correction on a per subsegment area basis using the representative point (steps related to z in the flowchart of FIG. 22 ).
  • the content of manipulation of the initial values of xh and yv and the values of xh and yv may be changed according to the switching of the pattern.
  • the initial values of xh and yv may be set to the maximum values (hmax and vmax), and xh and yv may be decremented by one until xh and yv reach the minimum value (0).
  • This change can change (for example, reverse) the processing target shifting order of the segment areas subjected to the light source lighting amount correction according to the pattern, in the same manner as the processing target shifting order of the subsegment areas in one pattern and the other pattern. Due to this, the light sources to be corrected for increasing the luminance can be easily dispersed. As a result, the load on the light sources can be further reduced.
  • Such a change in the processing target shifting order of the segment areas according to the switching of the pattern can be applied to the execution order of the light source lighting amount correction in the same manner.
  • FIG. 25 is a schematic diagram illustrating a setting example of the segment areas and the subsegment areas of the image display panel 30 according to a first modification.
  • the segment areas may be arranged along one direction, and the segment areas may be arranged in a staggered manner along another direction orthogonal to one direction.
  • the segment areas may be arranged in the X-direction to form rows of the segment areas and arranged in a staggered manner along the Y-direction to form a zigzag arrangement, for example.
  • the configuration of a plurality of subsegment areas included in one subsegment area is the same as that of the first embodiment. Either configuration of the first and second embodiments may be employed for the resetting of the luminance.
  • FIG. 26 is a diagram illustrating an arrangement example of light sources 51 a of a light source device 50 A according to the first modification.
  • two light sources may be assigned to one segment area as illustrated, for example, in FIG. 26 .
  • two light sources 51 a are assigned to one segment area and arranged at even intervals along the X-direction, and the light sources 51 a included in the light source device 50 A are arranged so as to be aligned in the row and column directions. Due to this, the resetting to the reset luminance for the segment area can be performed on a per light source 51 a basis.
  • the reset luminance of the segment area adjacent to a subsegment area in the X-direction or the Y-direction which is calculated using the first coefficient in the first embodiment, is reset for the segment areas
  • the reset luminance may be reflected in the lighting amount of the light source 51 a adjacent along the X-direction or Y-direction to the subsegment area for which the reset luminance is calculated. That is, the reset luminance may be reflected in some of the light sources 51 a , instead of all the light sources 51 a illuminating the segment areas. Due to this, a difference in luminance on a per subsegment area basis can be more easily reflected by the luminance distribution indicated by the light source drive signal BL with high fidelity.
  • the display device of the first modification may have a configuration in which the light sources 51 are assigned to the segment areas on a one-to-one basis described with reference to FIG. 3 .
  • the light sources 51 are arranged in a staggered manner in the Y-direction.
  • FIG. 27 is a schematic diagram illustrating a setting example of the segment areas and the subsegment areas of the image display panel 30 according to a second modification.
  • FIG. 28 is a diagram illustrating an arrangement example of light sources 51 b of a light source device 50 B according to the second modification.
  • the segment areas are arranged in a staggered manner in the other direction (Y-direction), and hence, both ends in one direction (X-direction) of the display area form gaps on a row-by-row basis.
  • a substantially half segment area H is provided so as to fill each of the gaps.
  • the segment area H is a segment area having one or more subsegment areas the number of which is halved in one direction.
  • the arrangement of the light sources 51 b of the light source device 50 B corresponds to the segment areas H.
  • a substantially half block I is a block for illuminating the segment area H.
  • the number of light sources 51 b arranged in the block I in one direction is half the number of light sources 51 b arranged in each of the blocks for illuminating the other segment areas. Either configuration of the first and second embodiments may be employed for the resetting of the luminance.
  • one direction may be the Y-direction
  • the other direction may be the X-direction
  • FIG. 29 is a schematic diagram illustrating a setting example of the segment areas and the subsegment areas of the image display panel 30 according to a third modification.
  • the two dividing lines for dividing the segment area into a plurality of subsegment areas do not extend along one direction (such as at least one of the X-direction and the Y-direction) in which the light sources 51 are arranged. That is, as illustrated in FIG. 29 , the two dividing lines, which are represented by dotted lines, may extend in oblique directions so as to form the diagonal lines of the rectangle of the segment area. Strictly speaking, the two dividing lines form stepped lines so as to trace border lines between the pixels 48 , and these steps extend along the directions of the diagonal lines. Either configuration of the first and second embodiments may be employed for the resetting of the luminance. In this case, in the adjacent light source lighting amount correction, using a light source of a segment area facing a side of the subsegment area has higher priority.
  • FIG. 30 is a schematic diagram illustrating a setting example of the segment areas and the subsegment areas of the image display panel 30 according to a fourth modification.
  • the number of the dividing lines for dividing one segment area into a plurality of subsegment areas is not limited to two.
  • the number of the dividing lines for dividing one segment area into a plurality of subsegment areas may be one, the dividing lines being represented by dotted lines.
  • the fourth modification illustrated in FIG. 30 gives an example in which only one of the two dividing lines illustrated in FIG. 29 is employed.
  • the other of the two dividing lines may be employed. Either configuration of the first and second embodiments may be employed for the resetting of the luminance. In this case, in the adjacent light source lighting amount correction, using a light source of a segment area facing a side of the subsegment area has higher priority.
  • FIG. 31 is a diagram illustrating a configuration example of a light source device 50 C according to a fifth modification.
  • the light sources of the light source device 50 C need not be provided directly below the segment areas.
  • the light source device 50 C may include a first sidelight light source 52 A and a second sidelight light source 52 B.
  • the first sidelight light source 52 A includes a plurality of light sources 56 A, 56 B, 56 C, 56 D, 56 E, and 56 F
  • the second sidelight light source 52 B includes a plurality of light sources 57 A, 57 B, 57 C, 57 D, 57 E, and 57 F.
  • the first sidelight light source 52 A and the second sidelight light source 52 B are arranged so that the light sources 56 A, 56 B, 56 C, 56 D, 56 E, and 56 F and the light sources 57 A, 57 B, 57 C, 57 D, 57 E, and 57 F are axisymmetric to each other with respect to a center line LXc in the light input direction.
  • the light sources 56 A, 56 B, 56 C, 56 D, 56 E, 56 F, 57 A, 57 B, 57 C, 57 D, 57 E, and 57 F are, for example, LEDs having the same color (such as white color). Either configuration of the first and second embodiments may be employed for the resetting of the luminance.
  • the adjacent light source lighting amount correction of the example illustrated in FIG. 31 is performed on segment areas adjacent to respective subsegment areas in the X-direction.
  • the light sources 56 A, 56 B, 56 C, 56 D, 56 E, and 56 F and the light sources 57 A, 57 B, 57 C, 57 D, 57 E, and 57 F extend along the X-direction, but may extend along the Y-direction. If the light sources extend along the Y-direction, the adjacent light source lighting amount correction is performed on segment areas adjacent to the respective subsegment areas in the Y-direction.
  • the first sidelight light source 52 A and the second sidelight light source 52 B illuminate the image display panel 30 , for example, through light guide plates.
  • the light guide plates are provided on the back side of the image display panel 30 , guide light in a direction orthogonal to the arrangement direction of the light sources 56 A, 56 B, 56 C, 56 D, 56 E, and 56 F and the light sources 57 A, 57 B, 57 C, 57 D, 57 E, and 57 F, and emit the light toward the image display panel 30 .
  • Only either of the first sidelight light source 52 A and the second sidelight light source 52 B needs to be provided.
  • Each of the first sidelight light source 52 A and the second sidelight light source 52 B may include any number of light sources.
  • FIG. 32 is a schematic diagram illustrating a setting example of the segment areas and the subsegment areas of the image display panel 30 according to the fifth modification.
  • the segment area is divided into a plurality of subsegment areas only in the X-direction serving as the arrangement direction of the light sources 56 A, 56 B, 56 C, 56 D, 56 E, and 56 F and the light sources 57 A, 57 B, 57 C, 57 D, 57 E, and 57 F.
  • the resetting and the correction may be performed by providing the subsegment areas with respect to one direction as exemplified in the fifth modification.
  • the embodiments and the like are not limited thereto.
  • three or more light sources may be assigned to one segment area.
  • the number of subsegment areas included in one segment area is not limited to two or four, but may be three, or five or more.
  • the pattern of the dividing lines for dividing one segment area into a plurality of subsegment areas is not limited to the examples of the embodiments and the like, but may be any pattern.
  • each of a plurality of segment areas is illuminated by one or more light sources, each of a plurality of light sources need not be assigned to one of the segment areas.
  • a plurality of segment areas may share the light source 56 A or the like.

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